Fundamentals, water, acids, bases and buffers

Question 1

Enzyme deficiency in alkaptonuria

Answer 1

Homogentisate oxidase

Question 2

Enzyme deficiency in homocystinuria

Answer 2

Cystathionine synthase

Question 3

Enzyme deficiency in MSUD

Answer 3

Branched-chain alpha-ketoacid dehydrogenase

Question 4

Enzyme deficiency in PKU

Answer 4

Phenylalanine hydroxylase

Question 5

Hydroxylation

Answer 5

Introduces an -OH group

Question 6

Decarboxylation

Answer 6

removes a carboxyl group and release CO2

Question 7

IN oxidation reactions electrons are ____

IN reduction reactions electrons are ____

Answer 7

Lost

Gained

Question 8

___% of our body wieght is water

Answer 8

50%

Question 9

Unique properties of water

Answer 9

Great nucleophile
Great buffer
Hydrogen bonds
Great solvent

Question 10

pH =

Answer 10

• log [H+]

Question 11

Hormones that monitor blood volume and osmolality

Answer 11

ADH and aldosterone

Question 12

Buffers consist of:

Answer 12

Undissosciated acid and its conjugate base

Question 13

A buffer has its greatest buffering cpacity at:

Answer 13

or near its pKa (+/- 1)

Question 14

pKa =

Answer 14

• log Ka

Question 15

Two factors that determine the effectiveness of a buffer

Answer 15

its pKa relative to the pH of a solution

and

its concentration

Question 16

Norma pH range for blood

Answer 16

7.35 - 7.45

Question 17

Blood pH is maintained by:

Answer 17

H2CO3/HCO3- buffer system

Question 18

Ka is:

Answer 18

acid dissociation constant, larger Ka, stronger acid

Question 19

pKa is:

Answer 19

• log Ka

smaller pKa, stronger acid

Question 20

Henderson-Hasselbalch equation:

Answer 20

pH = pKa + log [A-]/[HA]

Question 21

Normal metabolism generates:

Answer 21

CO2, lactic acids and ketones, and inorganic acids

Question 22

How does the body void of acid?

Answer 22

Expiration of CO2

Excretion of ammonium (NH4+)

Question 23

Respiratory acidosis caused by:

Answer 23

Hypoventilation > leads to an increase in CO2 > increase H+ > decreased pH

Question 24

Metabolic acidosis caused by:

Answer 24

Addition of a strong acid and loss of HCO3- (via diarrhea and/or abnormal kidney function)

Question 25

Buffer system equation (dont forget enzyme):

Answer 25

CO2 + H2O H2CO3 HCO3- + H+ Via carbonic anhydrase

Question 26

Respiratory alkalosis is caused by:

Answer 26

Hyperventillation > leads to decrease in CO2 > leads to loss of H+ > increased pH

Question 27

Metabolic alkalosis caused by:

Answer 27

Addition of a strong base and loss of acid (via vomiting)

Question 28

Gibbs free energy:

Answer 28

∆G = ∆H -T∆S

Question 29

-∆H vs +∆H

Answer 29

-∆H is favorable and leads to a lower energy state, heat flow out of the system +∆H is unfavorable and leads to higher energy state, heat flow into a system

Question 30

-∆S vs +∆S

Answer 30

-∆S more favorable as ti leads to increase in entropy +∆S less favorable as it leads to a decrease in entropy

Question 31

What is Keq

Answer 31

Equilibrium cosntant | Temperature dependent

Question 32

Keq =

Answer 32

[X]^x[Y]^y / [A]^a[B]^b for reaction: aA +bB xX + yY

Question 33

Standard state conditions

Answer 33

298K, 1M, 1 atm, pH 7

Question 34

∆G° vs ∆G°'

Answer 34

Gibbs free energy under standard conditions Same, but used for biochemistry purposes

Question 35

∆G° > 0 (+)

Answer 35

Endergonic non spontaneous favors reactants

Question 36

∆G° < 0 (-)

Answer 36

Exergonic spontaneous favors products

Question 37

Le Chatliers Principle

Answer 37

Systems at equilibrium will respond to applied stress with a shift that counteracts applied stress

Question 38

+∆H vs -∆H

Answer 38

Endothermimc Exothermic

Question 39

Chemical reaction that is crucial to creating energy currency ATP

Answer 39

Phosphoryl group transfer

Question 40

Favorability of ATP -> ADP + Pi

Answer 40

Very favorable ∆G << 0 ATP hydrolysis is useful in coupling reactions

Question 41

Cystine

Answer 41

When 2 Cysteine's come together by a disulfide bond

Question 42

Charge on α-amino group

Answer 42

pronated (+) at a pH 7

Question 43

Charge on α-carboxyl group

Answer 43

dissociated (-) at pH 7

Question 44

Charge on basic AA's

Answer 44

Arginine, lysine, histidine are positive at pH 7

Question 45

Charge on acidic AA's

Answer 45

Aspartic acid and glutamic acid are negative at pH 7

Question 46

Isoelectric point

Answer 46

Point at which overall charge on AA is 0

Question 47

If the pH is below pKa:

Answer 47

It will be pronated

Question 48

If the pH is above pKa:

Answer 48

It will be deprotonated

Question 49

pK1

Answer 49

α-carboxyl group (pKa ~2)

Question 50

pK2

Answer 50

α-amino group (pKa ~9)

Question 51

First line of defense against pH shift

Answer 51

Bicarbonate buffer Phosphate buffer Protein buffer (ie hemoglobin)

Question 52

Second line if defense against pH shift

Answer 52

``` Respiratory mechanism (excretion of CO2) Renal mechanism (excretion of H+) ```

Question 53

Why does a patient with severe anemia have a decreased capacity to use the bicarbonate buffer system?

Answer 53

Decreased amount of carbonic anhydrase in red blood cells

Question 54

Enzyme deficiency in homocystinuria:

Answer 54

Cystathione synthase

Question 55

Enzyme deficiency in alkaptonuria:

Answer 55

Homogentisate oxidase

Question 56

A class of chemical reactions that are of great importance in the formation of energy currency ATP

Answer 56

Phosphoryl group transfer